function Map(ele) {
    this.ele = ele
    // 不加px是为了方便以后计算
    this.width = 800
    this.height = 400
}
Map.prototype.create = function () {
    this.ele.style.width = this.width + 'px'
    this.ele.style.height = this.height + 'px'
    // 依靠平铺实现效果
    this.ele.style.background = 'url(./bg.png)'
    this.ele.style.border = '10px solid red'
    this.ele.style.position = 'relative'

}